Multiple-keyed flywheel and engine crankshaft

ABSTRACT

A multiple-keyed crankshaft and flywheel provides for different ignition timing options for an internal combustion engine. The crankshaft of the engine includes multiple keyways set at designated angular displacements of the crankshaft that correspond with keyways on a flywheel for providing different timing options for the engine. The flywheel may be mounted to the crankshaft by aligning one of the keyways of the flywheel to one of the keyways of the crankshaft related to a particular ignition timing selection.

This application is a continuation under 35 U.S.C. § 120 and 37 C.F.R. §1.53(b) of U.S. patent application Ser. No. 15/261,508 filed Sep. 9,2016, the disclosure of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD Background

Small internal combustion engines are used in a variety of devicesincluding, but not limited to: generators, chainsaws, lawn mowers, weedtrimmers, all-terrain vehicles, wood splitters, pressure washers, gardentillers, snow blowers, or other devices. A small engine often includes aflywheel disposed on a crankshaft. The flywheel stores rotational energyfrom the crankshaft or prime mover of an engine. Through momentum andinertia, from one or more of the series of strokes energy, is receivedfrom the crankshaft and then delivered to the crankshaft or prime moverin another one or more of the series of strokes. Various engine modelsmay include different relative arrangements of the flywheel and thecrankshaft. However, engine designs do not facilitate different relativearrangements in a single apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are described herein with reference to thefollowing drawings.

FIG. 1 illustrates an example internal combustion engine.

FIG. 2 illustrates an example internal combustion engine showingparticular systems of the engine.

FIG. 3 illustrates of a crankshaft of the engine of FIG. 1 or of FIG. 2.

FIG. 4 illustrates an example flywheel of the engine of FIG. 1 or ofFIG. 2.

FIG. 5 illustrates a detailed view of an example of a dual-keyedflywheel with varied offset and a crankshaft.

FIG. 6 illustrates a perspective of the flywheel and crankshaft of FIG.5.

FIG. 7 illustrates a detailed view of an example of a dual-keyedflywheel and a crankshaft with a varied offset of FIG. 5 in a firstposition.

FIG. 8 a detailed view of a further embodiment of an example of adual-keyed flywheel and a crankshaft with a varied offset of FIG. 5 in asecond position.

FIG. 9 illustrates another embodiment of a detailed view of an exampleof a dual-keyed flywheel with varied offset and a crankshaft.

FIG. 10 illustrates a perspective of the flywheel and crankshaft of FIG.9.

FIG. 11 illustrates a view of a varied dual-keyed flywheel offset anddual-keyed offset crankshaft configuration in connection with ignitionmodule of FIG. 9 in a first position.

FIG. 12 illustrates a view of a dual-keyed offset flywheel and varieddual-keyed offset crankshaft offset configuration in connection with anignition module of FIG. 9 in a second position.

FIG. 13 illustrates a view of a three-keyed flywheel in a firstposition.

FIG. 14 illustrates a view of a three-keyed flywheel in a secondposition.

FIG. 15 illustrates a view of a three-keyed flywheel in a thirdposition.

FIG. 16 illustrates a three-keyed crankshaft.

FIG. 17 illustrates an example flowchart for manufacturing a rotationalapparatus.

FIG. 18 illustrates an example flowchart for operation of rotationalapparatus.

FIG. 19 illustrates a controller for an internal combustion engine.

DETAILED DESCRIPTION

A small engine often includes a flywheel disposed on a crankshaft. Therotating flywheel includes a magnet that passes an ignition module fixedto the engine to control engine spark within a cylinder during thecompression stroke of the piston. Ignition timing varies for each engineand fuel type. Engine ignition timing may be based on the degrees beforetop dead center (“TDC”) of the piston within the cylinder where ignitionof the spark plug produces the most power and efficiency.

Ignition timing may vary for each engine and fuel type. The size of theengine cylinder and piston may affect ignition timing within an engine.Likewise, the type of fuel in combination with the engine (i.e. gaseousor liquid) may also affect the ignition timing of an engine. Each fueltype has an ideal burn rate and compression ratio that affects theignition timing of an engine. In some instances, the same engine mayoperate with different selected fuel types (i.e. gasoline, natural gas,propane, liquid propane, or others). In this situation, a design of theengine may include different ignition timing for the different fueltypes in order to obtain maximum power and efficiency. Each fuel typeachieves optimal power output at different timing positions of thepiston. Most engines include fixed ignition timing based on thepredetermined fuel type, where ignition timing is not selectable. Thereare, however, techniques for adjusting ignition timing in an engine.

One such technique is disclosed in U.S. Pat. No. 4,278,054 ('054) inwhich differently sized keys adjusts the timing. The '054 patentutilizes a flywheel with a single keyway and a shaft with a singlecorresponding keyway. The keyway of the flywheel is larger than that ofthe keyway in the shaft and the two are not angularly aligned. Thekeyway of the '054 patent is the element that adjusts the timing of theengine. The keyway is shaped as a “T” including a vertical member and anasymmetrical horizontal member. The vertical member of the key mateswith the shaft and the horizontal member mates with the flywheel. Theasymmetrical horizontal member of the T shaped keyway changes theangular displacement of the flywheel to the shaft. The '054 patentcontemplates different sized keys to adjust the angular orientation fromthe keyway of the shaft and the keyway of the flywheel. The longer thesymmetrical horizontal member of the T-shaped keyway, the greater theangular displacement of the keyways. The offset nature of the keyways isrequired to result in the rotational change between the flywheel andshaft that renders the change in the ignition timing.

A small engine may also modify ignition timing through use of anignition system controlled by a processor. In this instance, the systemmeasures the revolutions per minute (“rpm”) of the engine, and basedupon the rpm of the engine, the processor is programed to fire at aspecific angle for a particular speed range, such as 2400 rpm to 3600rpm. Timing is adjusted by activating a semiconductor switch whichinitiates transfer of electrical energy within the ignition system thatthen causes the spark plug to fire. The specific time to activate theswitch corresponds with a different timing angle as dictated by thecurve to control the firing which can occur at different times dependingon the desired requirements.

The following example systems include a multiple-keyed flywheel andcrankshaft for adjusting the ignition timing of an internal combustionengine. A crankshaft is a shaft within the engine to which theconnecting rods of pistons are connected and cause a rotational force. Aflywheel includes a rotational element that increases the engine'smomentum and provides stable rotation of the crankshaft. The flywheelincludes multiple keyways formed to accept a key and align with oneparticular keyway of the multiple keyways within a crankshaft to adjustthe ignition timing of the engine. A multiple-keyed crankshaft andflywheel provides for different ignition timing options for an internalcombustion engine. The crankshaft of the engine includes multiplekeyways set at designated angular displacements of the crankshaft thatcorrespond with keyways on a flywheel for providing different timingoptions for the engine. The flywheel may be mounted to the crankshaft byaligning one of the keyways of the flywheel to one of the keyways of thecrankshaft related to a particular ignition timing selection. A keywayis a slot cut in the flywheel and crankshaft for a key to be placed toensure correct orientation between the flywheel and crankshaft. The keyis the piece of shaped material inserted into a keyway to ensure properorientation of the flywheel and crankshaft.

FIG. 1 illustrates an example internal combustion engine 10. The engine10 may include: a piston 11, cylinder 12, crankshaft 14, key 15,flywheel 16, air cleaning system 20, ignition module 22 and spark plug34.

The engine 10 may be any type of engine 10 in which the combustion of afuel (e.g., gasoline or another liquid fuel) with an oxidizer (e.g.,air) in a chamber applies a force to a drive component (e.g., piston,turbine, or another component) of the engine 10. The drive componentrotates or otherwise moves to perform work. The engine 10 may power agenerator, chainsaw, lawn mower, weed trimmer, all-terrain vehicle, boatengine, go kart, wood splitter, pressure washer, garden tiller, snowblower, or another device. The engine 10 may be a two-stroke engine or afour-stroke engine. The number of cylinders of the engine 10 may vary toinclude one cylinder or multiple cylinders. The size of the engine 10may vary depending on the application. For example, the size of theengine or a chain saw may be 1.5 cubic inches to 2.8 cubic inches, thesize of the engine for a lawn mower may be 50 cubic inches to 149 cubicinches, and the size of the engine for an all-terrain vehicle may be 200cubic inches to 748 cubic inches. The size of the engine may be largeror smaller.

FIGS. 1 and 2 illustrate example internal and external components of theengine 10 or coupled with the engine 10. The external components mayinclude a crankshaft 14, flywheel 16, muffler, air cleaning system 20,and a control portion. The phrases “coupled with” or “coupled to”include directly connected to or indirectly connected through one ormore intermediate components. Additional, different, or fewer componentsmay be provided.

A fuel tank stores fuel (e.g., gasoline), which may be delivered to acarburetor. The carburetor may provide fuel to the cylinders 12 of theengine 10. At the same time, the air cleaning system delivers clean airfrom the air cleaning system 20 into the cylinders 12 to facilitatecombustion. Combustion within the cylinders 12 is caused by the ignitionmodule 22, which fires the spark plug 34, igniting the fuel air mixture.Timing of the ignition module 22 may be operated by the flywheel 16 asit rotates with the crankshaft 14 and passes a magnet 32 across theignition module 22. As a result of the combustion within the cylinders12, the piston 11 drives the crankshaft 14 to produce engine output.Following combustion, the exhaust is directed through a muffler and outof the engine 10.

The power and efficiency of the engine 10 may depend on the ignitiontiming of the engine 10. Depending on the fuel type (i.e. gasoline,natural gas, propane, or liquid propane) it may be necessary to usedifferent ignition timing settings of the engine 10. Changing theignition timing may be accomplished by selecting a specific position ofthe flywheel 16 and magnet 32 when coupled relative to the crankshaft14.

FIGS. 1 and 2 further depict the ignition module 22. The ignition module22 controls the firing of the spark plug 34 within the cylinders 12. Theignition module 22 may be mounted on the crankcase in a fixed positionlocated adjacent the flywheel 16. The ignition module 22 may include acharge coil, primary and secondary ignition coil, spark plug 34, highvoltage capacitor and a semiconductor switch. The capacitor is used tostore the electrical charge generated from the interaction of the magnet32 and the charge coil. The semiconductor switch, when activated, breaksthe electrical contact between the capacitor and a primary coil,transforming low energy at the primary coil to high energy at thesecondary coil which then causes spark plug 34 to fire in the combustionchamber. In a multi-cylinder engine, each cylinder may have an ignitionmodule. The ignition module 22 may be an inductive magneto ignitionmodule where energy can be developed by a current charge in the coilprimary or a capacitor magneto ignition module where a voltage charge isstored in a high voltage capacitor. In an inductive ignition system asthe magnet on the flywheel passes the ignition module, current isdeveloped in the coil primary and then the current path is disruptedwith the semiconductor switch, creating a voltage that flows throughtransformer action from the primary to the secondary coil causes thespark plug to fire. In a capacitive ignition system, a voltage capacitoris charged from a charge coil that is energized by the rotationalmovement of the magnet on the flywheel 16 passing the ignition module22. When the semiconductor switch is activated it causes that energy tobe transferred to the coil primary and secondary through transformeraction. A processor based control may also determine when activate thesemiconductor switch to fire the spark plug within a given rotationalspeed of the engine 10. The processor may receive a signal conveying therpm of the engine. Once the engine reaches the defined range of rpm, theprocessor may be programed to fire the spark plug when the crankshaft isat a specific angle.

FIG. 3 depicts a crankshaft 14 and key 15 of the engine 10. At one endof the crankshaft is the power output portion 24 and at the other end isthe flywheel mounting portion 26. The crankshaft 14 may also includecounterweights 21, main bearings journals 23, connecting rod journals25, and web 27. The crankshaft is supported within the engine by themain journals 23 near each end of the crankshaft. The main journal 23may be may be connected to counterweights 21. The counterweights 21balance the offset weight of the pistons 11 connected to the crankshaft14. The webs 18 are connected to the counterweights 21 and are attachedto the connecting rod journal 25. The connecting rod journal 25 spansthe space between the webs and supports the connecting rod and head ofthe piston 11. The crankshaft 14 depicted is configured for two pistons,however, a crankshaft set up to function with one or multiple pistons ispossible or different configurations of the pistons is also possible.The pistons 11 may be aligned in a V-shaped configuration or an inlineconfiguration. Where an engine includes a plurality of pistons thecrankshaft 14 may be modified to include a counterweight 21, web 18 andconnecting rod journal 25 or each piston 11 of the engine. The poweroutput 24 of the crankshaft 14 may be configured to drive a generator,lawnmower or other device through mechanical power. The flywheel driveportion 26 of the crankshaft 14 may include a tapered portion tofacilitate a press fit attachment of the flywheel 16 to the crankshaft14. The flywheel drive 26 of the crankshaft 14 may also be configuredwith a flange or other configurations to enable the flywheel 16 to beattached to the crankshaft 14. The flywheel drive portion 26 of thecrankshaft 14 as depicted includes a keyway 28. The keyway 28 may beused to align the flywheel 16 on the crankshaft 14 and to also maintainthe flywheel in the proper location. The crankshaft 14 and key 15 may beformed from any metal or alloy material. The material may include castiron, ductal iron, aluminum, chrome steel, or steel.

FIG. 4 depicts the flywheel 16 of the engine 10. The flywheel 16 mayinclude a center bore 30 with a keyway 28 that is sized to correspond toattach to the flywheel drive portion 26 of the crankshaft 14. Theflywheel 16 may be formed from any metal or alloy material. The materialmay include cast iron, ductal iron, aluminum, or chrome steel. The bore30 as depicted in FIG. 4 is configured to press fit onto the crankshaft14. The flywheel 16 may include a magnet 32 fastened to the edge of theflywheel 16. The magnet 32 may be mounted to the flywheel 16 to energizeand activate the ignition module 22. The magnet 32 may be fastened tothe flywheel 16 using screws or any other suitable method. The magnet 32rotating about the axis of the flywheel and crankshaft, passes theignition module 22, charging the coil or capacitor that when activatedthrough the semiconductor switch, sends a current to the spark plug 34causing it to fire within the cylinder. Each time the magnet 32 passesthe ignition module 22 it passes current to the spark plug 34. Somerevolutions of the cylinder and the spark plug energy is wasted (notused) as that cylinder will not be in a combustion stroke cycle. Thenumber of degrees from the cylinder position or TDC in which the magnetpasses the ignition module 22 may set the timing for the engine 10. Themagnet 32 may be advanced or retarded in an angular displacement fromTDC to set the firing of the engine when the crankshaft has not yetrotated past TDC or has rotated slightly past TDC when the piston is incompression. Modifying the timing of the firing of the spark plug may bedue to fuel not completely burning at the exact time the spark plugfires. In most instances, the timing of the engine will be based on theangle of the ignition timing before the crankshaft reaches TDC. This isknown as advancing the timing of the engine. This is done to account forthe fact that the fuel in the cylinder does not all burn the instant thespark plug fires and the combustion gasses take time to expand.

In operation, the crankshaft 14, flywheel 16, and ignition module 22 mayeach function together to appropriately time the firing of the sparkplug 34. Ignition timing of the engine 10 may depend on the angularorientation of the magnet 32 of the flywheel 16 from TDC of thecrankshaft 14. The ideal angular orientation of the magnet 32 andflywheel 16 may depend on the fuel type for the engine 10. The sameengine 10 may run a variety of different fuels: gasoline, natural gas,propane, or liquid propane for example. Each of these fuels have anideal timing of the firing of the engine 10 that depends on the burnrate and compression ratio of the fuel. For example, natural gas mayhave an ideal timing of a first setting of degrees from TDC (e.g., 37degrees before TDC, a range of 30-40 degrees before TDC, or a range of20-50 degrees before TDC), whereas propane may have an ideal timing of asecond setting of degrees before TDC (e.g., 27 degrees before TDC, arange of 20-30 degrees before RDC, or a range of 10-40 degrees beforeTDC).

FIG. 5 illustrates a detailed view of the crankshaft 14 and flywheel 16utilizing a dual-keyed configuration to provide two relative alignmentsbetween the crankshaft 14 and the flywheel 16, and accordingly twoignition timing options for the engine 10 using the same flywheel 16 andignition module 22. In this embodiment, two keyways (first keyway 38,second keyway 40) are formed on the crankshaft 14 and two keyways (firstkeyway 42, second keyway 44) are formed on the flywheel 16. The keywaysof the system may also be described as a first keyway, a second keyway,and a third keyway relating to the flywheel keyways and a fourth andfifth keyway related to the crankshaft keyways. Aligning the firstkeyway 38 of the crankshaft 14 and the first keyway 42 of the flywheel16 provides for a first ignition timing position option 17 and aligningthe second keyway 44 of the crankshaft 14 and the second keyway 44 ofthe flywheel 16 provides for a second ignition timing position option19.

In the dual-keyed configuration as depicted in FIG. 6, the crankshaft 14includes two keyways. A first keyway 38 is located on top of thecrankshaft 14 at TDC, and a second keyway 40 is located at apredetermined angle (e.g., 180 degrees) from TDC on the bottom of thecrankshaft 14. The flywheel 16 may include two keyways to correspondwith two desired options for ignition timing of the engine. A firstkeyway 42 may be included within the flywheel 16 and configured to alignwith the first keyway 38 of crankshaft 14 at TDC, setting a firstignition timing. The magnet 32 of the flywheel 16 may be fixed on theflywheel 16 at an angular orientation for the first of the desiredignition timing 17 for one of the particular fuel types. The magnet 32may be fixed to the flywheel 16 for the first desired ignition timing 17of a first setting of degrees before TDC (e.g. 20 degrees before TDC, arange of 18-22 degrees before TDC, or a range of 15-20 degrees beforeTDC). A second keyway 44 may be spaced apart from the other flywheelkeyway 42 in a range of 160 degrees to 180 degrees.

In order to ensure the correct keyways are aligned to relate to thecorrect ignition timing setup, the corresponding first crankshaft keyway28 and first flywheel keyway 42 may be sized or shaped differently thanthe second crankshaft keyway 40 and second flywheel keyway 44. Regardingthe size of each key and keyway for a same flywheel and crankshaftignition timing setting, it is possible where each key and keyway is thesame shape, however, the difference between the sizes, it will beapparent where one key does not fit in the incorrect keyways and thekeyways are visually different sizes. For example, two keys and keywaysof the same flywheel and crankshaft connection may both be square keysand keyways, one large and one small. In this configuration, the largekey and keyway would be of a sufficient size that the large key will notfit within the small keyways. Likewise, the small key and keyways may beof a sufficient size such that placing the key in either of the largekeyways may result in a fit that is loose, clearly indicating that thealignment is incorrect key. Other differently sized keys areadditionally possible. The key may also be different shapes so as to notfit within the incorrect setting. Possible keys and keyways shapesinclude, but are not limited to: square, flat, woodruff, taper, flatbottom, and feather.

As depicted in FIG. 7, the first keyway 38 of the crankshaft 14, thefirst flywheel keyway 42, and key 15 that correspond together may be adifferent size as compared to the second keyway 40 of the crankshaft 14,the second keyway 44 of the flywheel 16 and key 15. Similarly, the firstcrankshaft keyway 38 and first flywheel keyway 42 may have a differentshape, color, or material then the second crankshaft keyway 40 andsecond flywheel keyway 44. Further indicia may be placed on thecrankshaft 14 or flywheel 16 to facilitate the proper alignment of thekeyways to identify the desired ignition timing selection.

As depicted in FIG. 7, if the first ignition timing option 17 isutilized and the flywheel 16 is mounted to the crankshaft 14 where thefirst keyway 38 of the crankshaft 14 is aligned with the first keyway 42of the flywheel 16, the magnet 32 may have a position ignition timing ofa first setting before TDC (e.g. 20 degrees before TDC within a range oftolerance that may span +/−2 degrees, +/−5 degrees, or +/−10 degrees).As depicted in FIG. 8, if the second ignition timing option 19 isutilized and the second keyway 44 of the flywheel 16 is aligned with thesecond keyway 40 of the crankshaft 14, the magnet position may berotated in a range (e.g., a range of 10 to 20 degrees) about thecrankshaft 14 and have a position ignition timing in the range of 30-40degrees before TDC

An example of use of the dual-keyed configuration may be an engine 10configured to operate using propane or natural gas as the fuel, wherepropane requires an optimal ignition timing of a first number of degreesfrom TDC (e.g., 27 degrees before TDC) and natural gas requires anoptimal ignition timing of a second number of degrees before TDC (e.g.,37 degrees before TDC). If a user chooses to operate the engine 10 usingpropane, aligning the first keyway 38 of the crankshaft 14 and firstkeyway 42 of the flywheel 16 allows for the optimal timing of use ofpropane as the fuel type upon set up of the engine 10 and mounting ofthe flywheel 16 to the crankshaft 14. If, a user chooses to operate theengine 10 using natural gas, aligning the second keyway 44 of thecrankshaft 14 with the second keyway 44 of the flywheel 16 may allow forthe optimal timing of use of natural gas as the fuel type upon set up ofthe engine 10 and mounting of the flywheel 16 to the crankshaft 14.

By utilizing and aligning the first crankshaft keyway 38 and firstflywheel keyway 42 or utilizing the second crankshaft keyway 40 andsecond flywheel keyway 44, a technician may setup the engine 10 for thedesired or chosen fuel type without need for multiple flywheels ordifferent engines. The disclosed embodiments have the advantage ofreducing the present inventory of flywheels by modifying an existingflywheel to add an additional keyway. A manufacturer with an inventoryof flywheels containing one or more keyways may modify those flywheelsby adding (i.e. cutting) an additional keyway at the desiredpredetermined angle to correspond with the ideal ignition timing asdescribed above. In addition to modifying a flywheel, the crankshaft ofan existing engine may be modified by adding (i.e. cutting) anadditional keyway at the desired predetermined angle to correspond withthe ideal ignition timing as described above. A manufacturer may thentake inventory of engines and flywheels that were previouslymanufactured for one fuel type and modify the crankshaft and flywheel toallow the engine to operate with a different fuel type.

In addition, existing flywheels and/or crankshafts may be modified toinclude additional keyways, which provides the advantage of facilitatingchanging the fuel of an engine from one type to another. As describedabove, different fuels may have different optimal ignition timings. Anengine in operation using one fuel type (i.e. natural gas) may beswitched to operating using a different fuel type (i.e. propane). Byswitching fuel types, it may be necessary to change the ignition timingof the engine to obtain optimal efficiency and power. In addition tochanging the flywheel and modifying the ignition timing as describedherein, changing the fuel type over from one fuel to another may requirethat the spark plugs be changed and the air to fuel ratio of thecarburetor be adjusted by changing fuel system control components.

Depicted in FIGS. 9-12, is a further embodiment of the dual-keyedconfiguration that utilizes the dual-keyed configuration as describedabove, however, the placement of the keyways of the crankshaft 14 andkeyways of the flywheel are interchanged.

FIG. 9 illustrates a detailed view of the crankshaft 14 and flywheel 16utilizing a dual-keyed configuration to provide two relative alignmentsbetween the crankshaft 14 and the flywheel 16, and accordingly twoignition timing options for the engine 10 using the same flywheel 16 andignition module 22. In this embodiment, two keyways (first keyway 38,second keyway 40) are formed on the crankshaft 14 and two keyways (firstkeyway 42, second keyway 44) are formed on the flywheel 16. Aligning thefirst keyway 38 of the crankshaft 14 and the first keyway 42 of theflywheel 16 provides for a first ignition timing position option 17 andaligning the second keyway 40 of the crankshaft 14 and the second keyway44 of the flywheel 16 provides for a second ignition timing positionoption 19.

In the dual-keyed configuration as depicted in FIGS. 9 and 10, thecrankshaft 14 includes two keyways. A first keyway 38 is on top of thecrankshaft 14 near or at TDC and a second keyway 40 is located less than180 degrees from TDC of the crankshaft 14. The flywheel 16 may includetwo keyways to correspond with two desired options for ignition timingof the engine. A first keyway 42 may be included within the flywheel 16and configured to align with the first crankshaft keyway 38 at or nearTDC. The magnet 32 of the flywheel 16 may be fixed on the flywheel 16 atan angular displacement position that retards the crankshaft (includingthe connecting rod and piston head) before TDC when the magnet passesthe ignition module 22 when rotating. The angular orientation of one ofthe desired ignition timings is fixed at a first setting (e.g. 20degrees) from TDC. A second flywheel keyway 44 may be spaced apart fromthe first keyway 42 by a predetermined angle such as 180 degrees.

As depicted in FIG. 11, if the first ignition timing option 17 isutilized and flywheel 16 is mounted to the crankshaft 14 where the firstkeyway 38 of the crankshaft 14 is aligned with the first keyway 42 ofthe flywheel 16, the magnet 32 may have a position ignition timing of afirst setting (e.g. 26 degrees) before TDC. As depicted in FIG. 12, ifthe second ignition timing option 19 is utilized and the second keyway44 of the flywheel 16 is aligned with the second keyway 40 of thecrankshaft 14, the magnet 32 position may be rotated slightly about thecenter of the crankshaft 14 and have a position ignition timing degreeof a second setting (e.g. 20 degrees) from TDC. As depicted in FIGS. 11and 12, the second keyway is positioned on the crankshaft less than 180degrees from TDC in the clockwise direction. It is also possible toposition the second keyway less than 180 degrees from TDC in thecounter-clockwise direction. This would result in a second ignitiontiming option that has a larger angular displacement than the firstignition timing option 17.

Depicted in FIGS. 13-15, is a further embodiment including a three-keyedflywheel configuration and dual-keyed crankshaft to provide threerelative alignments between the crankshaft 14 and the flywheel 16, andaccordingly three ignition timing options for the engine 10 using thesame flywheel 16 and ignition module 22.

FIG. 13 illustrates a three-keyed configuration to provide threerelative alignments between the crankshaft 14 and the flywheel 16, andaccordingly three ignition timing options for the engine 10 using thesame flywheel 16 and ignition module 22. The flywheel 16 may includethree keyways (first keyway 40, second keyway 44, third keyway 46)spaced to correspond to three desired options for ignition timing of theengine. The corresponding crankshaft 14 may include two keyways (firstkeyway 38, second keyway 40) are formed on the crankshaft 14 (see thecrankshaft depicted in FIGS. 5 and 6). A first flywheel keyway 42 may beconfigured to align with the first crankshaft keyway 38 at TDC. Theother two flywheel keyways (44 and 46) may be configured to align withthe second keyway 40 of the crankshaft 14. The magnet 32 of the flywheel16 may be fixed on the flywheel 16 at an angular orientation of one ofthe desired ignition timings at a first setting of degrees (e.g. 20degrees before TDC). A second flywheel keyway 44 may be spaced apartfrom the first flywheel keyway 42 in a range of 160 degrees to 180degrees in a clockwise direction. A third flywheel keyway 46 may bespaced apart from the first flywheel keyway 42 in a range of 160 degreesto 180 degrees in a counterclockwise direction of the first keyway 42.

As depicted in FIG. 13, aligning the first keyway 38 of the crankshaft14 and the first keyway 42 of the flywheel 16 provides for a firstignition timing position option 17. Illustrated in FIG. 14, aligning thesecond keyway 40 of the crankshaft 14 and the second keyway 44 of theflywheel 16 provides for a second ignition timing position option 19.Illustrated in FIG. 15, aligning the second keyway 44 of the crankshaft14 and the third keyway 48 provides for a third ignition timing positionoption 50. Alternatively, the flywheel may be configured such that twoof the flywheel keyways are positioned on the flywheel to align with thefirst keyway 38 of the crankshaft.

A further embodiment is depicted in FIG. 13, where a three-keyedflywheel 16 is utilized with a dual-keyed crankshaft 14 (e.g.,crankshaft 14 of FIGS. 5 and 6). The configuration depicted in FIG. 13provides for three options for ignition timing of the engine 10. In thisembodiment, two keyways (first keyway 38, second keyway 40) are formedon the crankshaft 14 as depicted in FIG. 5 and three keyways (firstkeyway 40, second keyway 44, and third keyway 46) are formed on theflywheel 16. In the three-keyed configuration, the three keyways may bespaced apart approximately 120 degrees or in a range of 110 to 130degrees.

If the first ignition timing option 17 is utilized and the flywheel 16is mounted to the crankshaft 14 where the first keyway 38 of thecrankshaft 14 is aligned with the first keyway 42 of the flywheel 16,the magnet 32 may have a position ignition timing in a range of 20-30degrees before TDC. Utilizing the second ignition timing option 19 wherethe second keyway 44 of the flywheel 16 is aligned with the secondkeyway 40 of the crankshaft 14, the magnet 32 position may be rotated ina range of 10 to 20 degrees in a clockwise direction about the center ofthe crankshaft 14 and have a position ignition timing in the range of30-50 degrees before TDC. Utilizing the third ignition timing option 50where the third keyway 46 of the flywheel 16 is aligned with the secondkeyway 40 of the crankshaft 14, the magnet 32 position may be rotated ina range of 10 to 20 degrees in a counter clockwise direction about thecenter of the crankshaft and have a position ignition timing in therange of 0-20 degrees before TDC.

As an example, the engine 10 may be configured to operate using propane,natural gas or gasoline as the fuel, where propane requires an optimalignition timing of 27 degrees before TDC; natural gas requires anoptimal ignition timing of 37 degrees before TDC; and gasoline requiresan optimal ignition timing of 20 degrees before TDC. If a user choosesto operate the engine 10 using propane, aligning the first keyway 38 ofthe crankshaft 14 and first keyway 42 of the flywheel 16 allows for theoptimal timing of use of propane as the fuel type upon set up of theengine 10 and mounting of the flywheel 16 to the crankshaft 14. If, auser chooses to operate the engine 10 using natural gas, aligning thesecond keyway 44 of the crankshaft 14 with the second keyway 44 of theflywheel 16 may allow for the optimal timing of use of natural gas asthe fuel type upon set up of the engine 10 and mounting of the flywheel16 to the crankshaft 14. If, a user chooses to operate the engine 10using gasoline, aligning the second keyway 44 of the crankshaft 14 withthe third keyway 46 of the flywheel 16 may allow for the optimal timingof use of gasoline as the fuel type upon set up of the engine 10 andmounting of the flywheel 16 to the crankshaft 14.

Illustrated in FIG. 16, an alternative to the above three-keyedconfiguration of two keyways being formed on the crankshaft 14 and threekeyways formed within the flywheel 16, three keyways may be formed onthe crankshaft 14 and two keyways formed on the flywheel 16 as depictedin FIG. 9. In this embodiment, the flywheel 16 includes two keywaysspaced 180 degrees apart, where the magnet 32 may have a positionignition timing in a range of 20-30 degrees before TDC. The crankshaft14 may have a first keyway 38 at TDC and have a second keyway 38 may bespaced apart from the first crankshaft keyway 42 in a range of 160degrees to 180 degrees in a clockwise direction. A third keyway 48 maybe formed in the crankshaft 14 and may be spaced apart from the firstcrankshaft keyway 38 in a range of 160 degrees to 180 degrees in acounter clockwise direction of the second crankshaft keyway 40.

Additional keyways may be placed in the crankshaft 14 and additionalkeyways may be formed in the flywheel 16 to provide for four or moreignition timing options. Further, the multiple-keyed configuration ofthe present invention may be used in combination with the use of anignition system controlled by a processor as described above to providefor additional options for engine 10 ignition timing.

FIG. 17 illustrates an example flowchart for manufacturing a rotationalapparatus of a multiple-keyed crankshaft and flywheel. Additional,different, or fewer acts may be provided. The acts are performed in theorder shown or other orders. The acts may also be repeated.

At act S101, a mold for a crankshaft is formed. The mold includes aflywheel drive portion, multiple keyways, a power output shaft portion,counterweights, main journals, and rod journals. The flywheel driveportion is shaped to form a tapered longitudinal portion of thecrankshaft. The output shaft portion is shaped to form a cylindricalportion in line with the longitudinal portion of the crankshaft. Thecounterweights are shaped to form extended portions off of thelongitudinal portion of the crankshaft. The main journals and rodjournals are shaped to form offset cylindrical portions from thelongitudinal portion of the crankshaft. Alternatively, the keyways maybe formed by machining after the crankshaft is formed.

At act S103, a mold for a multiple-keyed flywheel is formed. The moldincludes a cylindrical shaped portion forming the flywheel, multiplekeyways, a center bore within the flywheel, and a magnet mountingportion. The center bore is cylindrically shaped and formed through theflywheel. The magnet mounting portion is shaped to accept a magnetfastened to the flywheel. Alternatively, the keyways may be formed bymachining after the flywheel is formed.

At act S105, a deformable material is injected or poured into thecrankshaft mold. The material may include cast iron, ductal iron,aluminum, chrome steel, or steel. The deformable material takes theshape of the mold. In one example, as the deformable material cools, thedeformable material hardens to a rigid material. In another example,heating, curing or another technique is used to harden the deformablematerial into the crankshaft.

At act S107, a deformable material is injected or poured into theflywheel mold. The material may include cast iron, ductal iron,aluminum, chrome steel, or steel. The deformable material takes theshape of the mold. In one example, as the deformable material cools, thedeformable material hardens to a rigid material. In another example,heating, curing or another technique is used to harden the deformablematerial into the flywheel.

At act S109, the crankshaft including the hardened material is removedfrom the mold. The crankshaft includes multiple keyways, a flywheeldrive portion, a power output shaft portion, counterweights, mainjournals, and rod journals. The crankshaft may be further machined toachieve the desired dimension, shape or finish.

At act S111, the flywheel including the hardened material is removedfrom the mold. The flywheel includes a cylindrical shaped portionforming the flywheel, a keyway, a center bore within the flywheel, and amagnet mounting portion. The flywheel may be further machined to achievethe desired dimension, shape or finish.

At act S113, the crankshaft, including the flywheel drive portion,multiple keyways, power output shaft portion, counterweights, mainjournals, and rod journals are machined to obtain the desired dimension,shape and surface quality of each part.

At act S115, the flywheel, including the cylindrical shaped portionforming the flywheel, keyway, center bore within the flywheel, andmagnet mounting portion are machined to obtain the desired dimensionsand surface quality of each part.

At act S117, a magnet is mounted to the flywheel using fasteners and/ora mounting bracket. The magnet may be secured to the circumference ofthe flywheel at the desired angular displacement to TDC in order toalign with the ignition module of the engine. The location in which themagnet may be determined based on the fuel types used and number ofkeyways of the crankshaft and keyways of the flywheel. Each fuel typehas an ideal timing of the firing of the engine that depends on the burnrate and compression ratio of the fuel. For example, natural gas mayhave an ideal timing of 37 degrees before TDC. The magnet may then bemounted to the edge of the flywheel at a location where an alignedflywheel key and crankshaft key, when the magnet rotation passes theignition module the piston is 37 degrees before TDC.

FIG. 18 illustrates an example flowchart for installing a multiple keyedcrankshaft on a multiple keyed flywheel. Additional, different, or feweracts may be provided. The acts are performed in the order shown or otherorders. The acts may also be repeated.

At act, S201, a technician may determine the fuel type to be used in theengine types (i.e. gasoline, natural gas, propane, liquid propane, orothers). Certain engines may be able to operate with different fueltypes with little to no modification. In this circumstance, in order toobtain optimal performance of the engine the ignition timing of theengine may need to be adjusted. Each fuel type has an ideal burn rateand compression ratio that affects the ignition timing of an engine.Ignition engine timing may be based on the angular displacement of thecrankshaft from TDC of the piston within the cylinder where ignition ofthe spark plug produces the most power and efficiency. The crankshaftand flywheel may have a keyway, establishing the ideal timing for eachfuel type operation of the engine. For example, a flywheel that has twokeyways and a crankshaft that has two keyways, one keyway for propaneand another configured for natural gas using indicia.

At act S203, the technician may identify the correct flywheel andcrankshaft keyway that may be associated with the chosen fuel type. Eachkeyway of the flywheel and crankshaft will be associated with the idealtiming for a particular fuel type. Indicia may be used to identify whichkeyway on the flywheel and crankshaft relate to a fuel type. Forexample, if it is determined that natural gas is the chosen fuel type,the technician may identify the keyways on the flywheel and crankshaftdesignated for natural gas.

At act S205, the center bore of the flywheel may be aligned with thecrankshaft, and the flywheel may be mated onto the crankshaft. Theflywheel may be slid on to the crankshaft but not secured or fastenedthereto in order for the crankshaft and flywheel keyways to be aligned.

At act S207, the keyway of the flywheel is aligned with a selected oneof the two keyways of the crankshaft that corresponds to the selectedfuel type from act S201. These aligned keyways may be a different sizeas compared to the other keyway of the crankshaft and flywheel.Similarly, the aligned keyways may have a different shape, color, ormaterial then the other keyways of the flywheel and crankshaft.

At act 209, a key may be inserted to the aligned flywheel keyway andcrankshaft keyway. The key may be a snug fit, but with sufficientclearance to slide in the aligned keyways. Each key for different fueltypes may be different and may be configured to correspond to the uniquesize or shape of the aligned keyways so as to only fit within thecorrectly aligned keyways. The key corresponding to a one fuel type ascompared to keys for other fuel types may have a different shape, color,or material then the other keyways of the flywheel and crankshaft.

At act 211, the aligned flywheel and crankshaft are press fit together.The flywheel is manipulated onto the crankshaft and a bolt and washer isused to fix the press fit connection. The press fit connect sufficientlyconnects the flywheel and crankshaft and fixes them in place.

FIG. 19 illustrates a controller for monitoring an engine under load todetermine the performance and efficiency in connection with timingadjustments.

The controller 60 may include a processor 62, an input device 64, acommunication interface 66, a memory 68, and a display 70. Thecontroller 60 may receive data from sensors or other input devices. Inone instance, the controller 60 may receive measured oxygen levels orthe difference between the amount in oxygen in the exhaust and the airfrom an oxygen sensor and use that data to determine the amount of fuelburned at the engine's presently set timing. Based on the presently setkeyway selections and measured values from the oxygen sensor, thecontroller may identify which other keyway of a crankshaft to align withone of the other keyways of the flywheel. In another instance, thecontroller 60 may access memory 68 for a predetermined timing settingthat corresponds to an identification of which keyway of a crankshaft toalign with one of the keyways of the flywheel.

The controller may convey this identification using indicia disposed onthe flywheel and crankshaft. The input device 64 may be a hand helddevice for inputting commands or selections into the processor 62. Thecommands or selection may relate to fuel type settings, ignition timingsettings, or air to fuel mixture settings. The display 70 may beintegrated with the input device 64 or supplied by workstation 74. Thedatabase 76 may include settings for the engine 10 or the ignitionmodule 22, including ignition timing settings fuel type settings, ordata obtained from sensors. This information may be included in a tableand stored in the memory 68. Additional, different, or fewer componentsmay be included.

The sensing circuit 72 may be a rotation meter, tachometer, ordynamometer, where the rotational speed of the engine is calculatedand/or monitored. The sensing circuit 72 may be utilized with theprocessor 62 to further change the timing of the engine to gain advancedefficiency or power. In this instance, an electronically controlledignition system measures the rpm of the engine, and based upon the rpmof the engine, the processor 62 is programed to fire at a specific anglefor a particular speed range.

The sensing circuit 72 may also include gas sensors for monitoring theair into the engine and exhaust out of the engine to evaluate theengine's performance based on the selected timing. Example gas sensorsmay include one or more of oxygen sensor, carbon dioxide sensor, carbonmonoxide, or an emission sensor. It may be desirable to adjust theengine timing after performance and efficiency of the engine aredetermined by a sensor of the sensing circuit 72 for an engine underload. The sensor may measure air into the engine and exhaust andevaluate the oxygen level, burn efficiency and residual unused fuel todetermine if ignition timing should be adjusted. The sensor may thentransmit obtained data to the controller 60. Other types of sensors forthe sensing circuit 72 includes: motion sensors, temperature sensors,speed sensors, pressure sensors, torque sensor and internal enginesensors.

The processor 62 may control the engine, ignition module 22 or ignitionsystem. The processor 62 may control the speed of the engine or firingof the spark plug based on the output of any of these sensors. Theprocessor 62 may further control the ignition timing or a chargingsystem of the engine. The processor 62 may calculate the horsepower ofthe engine. The processor 62 may also be used to evaluate output ofsensors and sensing circuit to enhance engine performance and efficiencysuch as exhaust output. The oxygen in and exhaust output informationcollected by the sensors described above, may be analyzed by theprocessor which then determines if advancing or retarding ignitiontiming is appropriate when the engine is under load. The processor 62may include a general processor, digital signal processor, anapplication specific integrated circuit (ASIC), field programmable gatearray (FPGA), analog circuit, digital circuit, combinations thereof, orother now known or later developed processor. The memory 68 may be avolatile memory or a non-volatile memory. The memories may include oneor more of a read only memory (ROM), random access memory (RAM), a flashmemory, an electronic erasable program read only memory (EEPROM), orother type of memory. The memory 68 may be removable from the controller60, and the memory 68 may be removable from the engine, such as a securedigital (SD) memory card.

The communication interface 66 may include a physical interface, anelectrical interface, and/or a data interface. The communicationinterface 66 provides for wireless and/or wired communications in anynow known or later developed format. In addition to ingress ports andegress ports, the communication interface 66 may include any operableconnection. An operable connection may be one in which signals, physicalcommunications, and/or logical communications may be sent and/orreceived. An operable connection may include a physical interface, anelectrical interface, and/or a data interface.

The communication interface 66 may be connected to a network. Thenetwork may include wired networks (e.g., Ethernet), wireless networks,or combinations thereof. The wireless network may be a cellulartelephone network, an 802.11, 802.16, 802.20, or WiMax network. Further,the network may be a public network, such as the Internet, a privatenetwork, such as an intranet, or combinations thereof, and may utilize avariety of networking protocols now available or later developedincluding, but not limited to TCP/IP based networking protocols.

Any of the techniques described above may be embodied on anon-transitory computer readable medium, which may be a single medium ormultiple media, such as a centralized or distributed database, and/orassociated caches and servers that store one or more sets ofinstructions. The term “non-transitory computer-readable medium” shallalso include any medium, except a signal per se, that is capable ofstoring, encoding or carrying a set of instructions for execution by aprocessor or that cause a computer system to perform any one or more ofthe methods or operations disclosed herein.

In a particular non-limiting, exemplary embodiment, thecomputer-readable medium can include a solid-state memory such as amemory card or other package that houses one or more non-volatileread-only memories. Further, the computer-readable medium can be arandom access memory or other volatile re-writable memory. Additionally,the computer-readable medium can include a magneto-optical or opticalmedium, such as a disk or tapes or other storage device to capturecarrier wave signals such as a signal communicated over a transmissionmedium. A digital file attachment to an e-mail or other self-containedinformation archive or set of archives may be considered a distributionmedium that is a tangible storage medium. Accordingly, the disclosure isconsidered to include any one or more of a computer-readable medium or adistribution medium and other equivalents and successor media, in whichdata or instructions may be stored. The computer-readable medium may benon-transitory, which includes all tangible computer-readable media.

In an alternative embodiment, dedicated hardware implementations, suchas application specific integrated circuits, programmable logic arraysand other hardware devices, can be constructed to implement one or moreof the methods described herein. Applications that may include theapparatus and systems of various embodiments can broadly include avariety of electronic and computer systems. One or more embodimentsdescribed herein may implement functions using two or more specificinterconnected hardware modules or devices with related control and datasignals that can be communicated between and through the modules, or asportions of an application-specific integrated circuit. Accordingly, thepresent system encompasses software, firmware, and hardwareimplementations.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Additionally, the illustrations are merely representational and may notbe drawn to scale. Certain proportions within the illustrations may beexaggerated, while other proportions may be minimized. Accordingly, thedisclosure and the figures are to be regarded as illustrative ratherthan restrictive.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings and describedherein in a particular order, this should not be understood as requiringthat such operations be performed in the particular order shown or insequential order, or that all illustrated operations be performed, toachieve desirable results. In certain circumstances, multitasking andparallel processing may be advantageous. Moreover, the separation ofvarious system components in the embodiments described above should notbe understood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b) and is submitted with the understanding that it will not be usedto interpret or limit the scope or meaning of the claims. In addition,in the foregoing Detailed Description, various features may be groupedtogether or described in a single embodiment for the purpose ofstreamlining the disclosure. This disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may be directed toless than all of the features of any of the disclosed embodiments. Thus,the following claims are incorporated into the Detailed Description,with each claim standing on its own as defining separately claimedsubject matter.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention. The claims should not be read as limited to thedescribed order or elements unless stated to that effect. Therefore, allembodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

We claim:
 1. An apparatus comprising: a shaft comprising a first shaftslot and a second shaft slot; a rotational element comprising a magnetfor use with an ignition module and a center bore comprising a firstrotational element slot and a second rotational element slot on acircumference of the center bore; and a key configured to align thefirst shaft slot to the first rotational element slot in a firstposition corresponding to a first ignition timing option and configuredto align the second shaft slot to the second rotational element slot ina second position corresponding to a second ignition timing option. 2.The apparatus of claim 1, wherein the key aligns the shaft and therotational element in the first position corresponding to a first fueltype and aligns the shaft and the rotational element in the secondposition corresponding to a second fuel type.
 3. The apparatus of claim1, wherein the first shaft slot and the second shaft slot are differentsizes and the first rotational element slot and the second rotationalelement slot are different sizes.
 4. The apparatus of claim 3, whereinthe key is configured to mate with the first shaft slot and the firstrotational element slot or the second shaft slot and the secondrotational element slot.
 5. The apparatus of claim 1, wherein a portionof the shaft is tapered to accept the rotational element.
 6. Theapparatus of claim 1, wherein the rotational element further comprises athird rotational element slot, and wherein the key aligns the secondshaft slot to the third rotational element slot in a third positioncorresponding to a third ignition timing option.
 7. The apparatus ofclaim 1, wherein the shaft further comprises a third shaft slot, andwherein the key aligns the first rotational element slot or the secondrotational element slot to the third shaft slot in a third positioncorresponding to a third ignition timing option.
 8. The apparatus ofclaim 1, wherein the first rotational element slot includes indiciaassociated with the first shaft slot.
 9. The apparatus of claim 1,wherein the shaft is a crankshaft.
 10. The apparatus of claim 1, whereinthe rotational element is a flywheel.
 11. The apparatus of claim 1,wherein the first shaft slot, the second shaft slot, the firstrotational element slot, and the second rotational element slot arekeyways.
 12. The apparatus of claim 1, wherein the first ignition timingoption corresponds to the magnet at a first setting of degrees from topdead center (TDC) of the shaft, and wherein the second ignition timingoption corresponds to the magnet at a second setting of degrees from theTDC of the shaft.
 13. A method for installing a rotational apparatus foruse in an internal combustion engine, the method comprising: determiningan ignition timing setting for the internal combustion engine;identifying a first slot of a plurality of slots formed on a center boreof a rotational element and a second slot of a plurality of slots formedon a shaft of the engine that correspond to the determined ignitiontiming setting; mounting the rotational element on the shaft byinserting the shaft through the center bore; and aligning the first slotof the rotational element with the second slot of the shaft with a keythat is configured to mate with the identified slot of the rotationalelement and the identified slot of the shaft.
 14. The method of claim13, wherein the identified first slot of the rotational element has adifferent size than other slots of the plurality of slots formed on thecenter bore of the rotational element.
 15. A method for manufacturing arotational apparatus for use in an internal combustion engine, themethod comprising: forming a center bore with a first rotational elementslot and a second rotational element slot on a circumference of thecenter bore within a rotational element; and joining a magnet to therotational element at a predetermined angular orientation; wherein thefirst rotational element slot and the second rotational element slotcorrespond to a first shaft slot and a second shaft slot formed on adistal end of a shaft of the engine, and wherein a key aligns the firstshaft slot to the first rotational element slot in a first positioncorresponding to a first ignition timing option or aligns the secondshaft slot to the second rotational element slot in a second positioncorresponding to a second ignition timing option.
 16. The method formanufacturing the rotational apparatus of claim 15, wherein the firstshaft slot and the second shaft slot are different sizes and the firstrotational element slot and the second rotational element slot aredifferent sizes, and wherein the key is configured to mate the firstshaft slot and the first rotational element slot or the second shaftslot and the second rotational element slot.
 17. The method formanufacturing the rotational apparatus of claim 15, wherein the firstignition timing option corresponds to the magnet at a first setting ofdegrees from top dead center (TDC) of the shaft, and wherein the secondignition timing option corresponds to the magnet at a second setting ofdegrees from the TDC of the shaft.
 18. The method for manufacturing therotational apparatus of claim 15, wherein the shaft is a crankshaft. 19.The method for manufacturing the rotational apparatus of claim 15,wherein the rotational element is a flywheel.
 20. The method formanufacturing the rotational apparatus of claim 15, wherein the firstshaft slot, the second shaft slot, the first rotational element slot,and the second rotational element slot are keyways.